Identification of genes in Arabidopsis thaliana with homology to a novel acyl-glucose dependent glucosyltransferase of carnations

Recently, we characterized an acyl-glucose : anthocyanin 5-O-glucosyltransferase (DcAA5GT) in Dianthus caryophyllus that has novel characteristics. We also showed that a homologous enzyme, acyl-glucose:anthocyanin 7-O-glucosyltransferase (DgAA7GT), is present in Delphinium grandiflorum. These enzymes are both classified as members of glycoside hydrolase family 1 (GH1). Here, we searched the Arabidopsis thaliana database for genes with homology to DcAA5GT and DgAA7GT and identified 11 β-glucosidases (BGLU1–11) of unknown function. In a co-expression analysis, using genes for enzymes involved in anthocyanin modification as baits, we found that expression of AtBGLU6 and AtBGLU9 appeared to be correlated to that of the baits. Real-time RT-PCR showed that AtBGLU1, 6, 7 and 9 were expressed at their highest levels in anthocyanin-inducing medium, although AtBGLU6 was a pseudogene in which there was a stop codon on the middle of its cDNA sequence. These results suggest that AtBGLU1, 7 and 9 might be candidate glucosyltransferases for anthocyanin/flavonoid modification or biosynthesis.